The invention relates to improvements in apparatus for manipulating elongated objects, and more particularly to improvements in apparatus for manipulating rolls in calenders and like machines wherein groups of rolls are mounted in a frame and individual rolls must be exchanged from time to time for the purposes of inspection, repair or replacement. Still more particularly, the invention relates to improvements in apparatus of the type wherein a platform is provided with means for releasably supporting and moving rolls to and from prescribed positions for such rolls in the frames of supercalenders and like machines.
A supercalender comprises elastic rolls, hard rolls and guide rolls. It is often necessary to exchange damaged elastic rolls as well as to temporarily remove guide rolls which are used in such machines to establish a predetermined path for a running web of paper or other sheet-like material which is treated in the machine. Heretofore, a defective elastic roll was removed by a crane. Such mode of manipulating elastic rolls is not entirely satisfactory because a crane cannot be moved in front of a calender, so that it could engage a selected elastic roll, because the space in front of the elastic rolls is occupied by the aforementioned guide rolls. Furthermore, a crane cannot be used to directly engage the relatively short stubs at the axial ends of an elastic roll, mainly because of the presence of heating elements at the axial ends of hard rolls which are installed adjacent certain elastic rolls to define with the elastic rolls nips for the passage of a running web of paper or the like. Therefore, it is necessary to employ sleeves which must be slipped over the stubs at the axial ends of the elastic rolls in order to be engaged by a crane. Each such sleeve weighs several hundred kilograms so that a crane must be used to transport the sleeves to proper positions at the ends of a selected elastic roll which is to be removed from the frame of a supercalender. It is necessary to rely on workmen who guide the sleeves during that stage which involves introduction of stubs into the sleeves preparatory to removal of a roll from the frame of the supercalender. Such mode of exchanging rolls is time-consuming and necessitates the exertion of a pronounced effort by the attendants. The platform of a conventional apparatus is designed to move up and down along the supercalender so that the attendant or attendants can be moved to a desired level for proper manipulation of the sleeves as well as for the application or removal of screws, bolts or other threaded fasteners which are used to fix the bearings for the rolls to, or to separate such bearings from, the frame.
As a rule, a defective roll which is removed from the frame of a supercalender is transferred into a magazine. This involves a transport of the roll at a level above the platform. The attendants must leave the platform during such transfer of a roll for the reasons of safety. The same holds true during transfer of a fresh or repaired roll from the magazine into the supercalender.
Since the guide rolls are normally attached to the bearings for the adjacent elastic rolls, removal of an elastic roll from the frame of a supercalender further involves removal of the corresponding guide roll and temporary storage of the removed guide roll in the magazine. This necessitates the use of a relatively large magazine which must accommodate elastic rolls as well as guide rolls, and additional time is wasted for the transfer of guide rolls from the machine all the way into a magazine and back into the machine.
Commonly owned U.S. Pat. No. 4,685,390 granted Aug. 11, 1987 to Pav et al. discloses a calender with exchangeable rolls.
Certain types of conveyors for transport of commodities along horizontal paths are disclosed on pages T72, T73 and T76 of "Taschenbuch fur Maschinenbau" by Dubbel (published 1987 by Springer-Verlag).